Electronic device manufacturers strive to produce a rich interface for users. Conventional electronic devices often provide visual and/or auditory feedback to communicate information to users. In some cases, kinesthetic feedback (such as active and resistive force feedback) and/or tactile feedback (such as vibration, texture, and heat) may also be provided to the user to enhance the user experience. Generally speaking, kinesthetic feedback and tactile feedback are collectively known as “haptic feedback” or “haptic effects.” Haptic feedback may be useful for providing cues to alert the user of specific events or to provide realistic feedback sensations to create a greater sensory experience. Haptic feedback can be used with common electronic devices and even devices used for creating a simulated or virtual environment.
In order to generate haptic effects, some type of haptic actuator can be utilized. Examples of known haptic actuators include electromagnetic actuators, such as an Eccentric Rotating Mass (“ERM”) in which an eccentric mass is moved by a motor, a Linear Resonant Actuator (“LRA”) in which a mass attached to a spring is driven back and forth, a “smart material” such as piezoelectric material, electro-active polymers, or shape memory alloys, etc. Many of these actuators and the devices with which they interact typically have resonant frequencies, which can be built in or dynamically determined. Drive signals can be applied to the actuators to generate the haptic effects effectively and efficiently.